Each of us is supplied with a variety of specialized “white” cells, namely macrophages, T-cells, B-cells, and antibodies. These cells are infused with shared chemical markers, and they all team up to fight hordes of invading bacteria at the site of an infection. After the battle is fought its memory lives on, so the next time your body faces the same infection, it can be defeated much more effectively.
Add to that the huge amount and variety of other mostly benign creatures that reside inside, and they could all comprise a visual—albeit ghostly—walking proxy of yourself. Just don’t lend them your credit cards if they decide to take a vacation from your body.
And if knowing that you are a walking biological repository of minute monsters doesn’t set well with your sense of unsullied sterility, then you could do worse than have to take a regime of strong antibiotics to help your white cells fight your infection. Except that you’d be destroying a bunch of benign critters in the mix, or at least upsetting their balance in your body for years to come.